Like numerous other mechanical devices that contain many moving parts, hydraulically-actuated fuel injectors tend to have a break-in period. Engineers have observed that the amount of fuel actually injected from a hydraulically-actuated fuel injector will grow over time until reaching a steady state after a break-in period. In other words, engineers have observed that, for a fixed activation on-time, the amount of fuel actually injected from a hydraulically-actuated fuel injector can typically increase a measurable percentage over an initial break-in period, which is typically on the order of hours of operation. This increased output from the fuel injection system often reveals itself as power growth in the engine in which the fuel injectors are mounted.
In a typical hydraulically-actuated electronically-controlled fuel injection system, an electronic control module commands the individual fuel injectors to activate for an on-time that is determined from a number of sensor inputs. For instance, the activation on-time for an individual injector will preferably be optimized for a particular performance parameter based upon a number of sensor inputs to the electronic control module, including engine speed and load conditions, throttle position, etc. Instead of continuously calculating preferred fuel injection on-times during the operation of the engine, the electronic control module typically includes or has access to a memory unit containing a multi-dimensional map having recorded injector on-times for each different combination of operation variables. Once established, the recorded map of injector on-times are not adjusted to compensate for performance changes that naturally occur during the break-in period of new fuel injectors. In some instances, particularly relating to smaller sized engines, the power growth observed due to the fuel injector break-in phenomenon is less than desirable.
The present invention is directed to sensing changes in, and adjusting, fuel injection system operation to control performance output of the injection system.